[coverage] Block coverage with support for IfStatements

src/interpreter/bytecode-generator.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/interpreter/bytecode-generator.h"
 
 #include "src/ast/compile-time-value.h"
 #include "src/ast/scopes.h"
 #include "src/builtins/builtins-constructor.h"
 #include "src/code-stubs.h"
@@ skipping 719 matching lines @@
     const AstRawString* name;
     FeedbackSlot slot;
     FeedbackSlot literal_slot;
     FunctionLiteral* func;
   };
   ZoneVector<Declaration> declarations_;
   size_t constant_pool_entry_;
   bool has_constant_pool_entry_;
 };
 
+// Used to generate IncBlockCounter bytecodes and the {source range, slot}
+// mapping for block coverage.
+class BytecodeGenerator::BlockCoverageBuilder final : public ZoneObject {
+ public:
+  explicit BlockCoverageBuilder(Zone* zone, BytecodeArrayBuilder* builder)
+      : slots_(0, zone), builder_(builder) {}
+
+  static const int kNoCoverageArraySlot = -1;
+
+  int AllocateBlockCoverageSlot(SourceRange range) {
+    if (range.IsEmpty()) return kNoCoverageArraySlot;
+    const int slot = static_cast<int>(slots_.size());
+    slots_.emplace_back(range);
+    return slot;
+  }
+
+  void IncBlockCounter(int coverage_array_slot) {
+    if (coverage_array_slot == kNoCoverageArraySlot) return;
+    builder_->IncBlockCounter(coverage_array_slot);
+  }
+
+  const ZoneVector<SourceRange>& slots() const { return slots_; }
+
+ private:
+  // Contains source range information for allocated block coverage counter
+  // slots. Slot i covers range slots_[i].
+  ZoneVector<SourceRange> slots_;
+  BytecodeArrayBuilder* builder_;
+};
+
 class BytecodeGenerator::CurrentScope final {
  public:
   CurrentScope(BytecodeGenerator* generator, Scope* scope)
       : generator_(generator), outer_scope_(generator->current_scope()) {
     if (scope != nullptr) {
       generator_->set_current_scope(scope);
     }
   }
   ~CurrentScope() {
     if (outer_scope_ != generator_->current_scope()) {
@@ skipping 10 matching lines @@
     : zone_(info->zone()),
       builder_(new (zone()) BytecodeArrayBuilder(
           info->isolate(), info->zone(), info->num_parameters_including_this(),
           info->scope()->num_stack_slots(), info->literal(),
           info->SourcePositionRecordingMode())),
       info_(info),
       ast_string_constants_(info->isolate()->ast_string_constants()),
       closure_scope_(info->scope()),
       current_scope_(info->scope()),
       globals_builder_(new (zone()) GlobalDeclarationsBuilder(info->zone())),
+      block_coverage_builder_(nullptr),
       global_declarations_(0, info->zone()),
       function_literals_(0, info->zone()),
       native_function_literals_(0, info->zone()),
       object_literals_(0, info->zone()),
       array_literals_(0, info->zone()),
       execution_control_(nullptr),
       execution_context_(nullptr),
       execution_result_(nullptr),
       generator_jump_table_(nullptr),
       generator_state_(),
       loop_depth_(0) {
   DCHECK_EQ(closure_scope(), closure_scope()->GetClosureScope());
+  if (info->is_block_coverage_enabled()) {
+    DCHECK(FLAG_block_coverage);
+    block_coverage_builder_ =
+        new (zone()) BlockCoverageBuilder(zone(), builder());
+  }
 }
 
 Handle<BytecodeArray> BytecodeGenerator::FinalizeBytecode(Isolate* isolate) {
   AllocateDeferredConstants(isolate);
+

[marja, 2017/06/02 07:01:23]

Since you're touching this, can you add a DCHECK here that we're in the main
thread?

[jgruber, 2017/06/02 07:18:31]

Done.

+  if (info()->is_block_coverage_enabled()) {
+    info()->set_coverage_info(
+        isolate->factory()->NewCoverageInfo(block_coverage_builder_->slots()));
+  }
+
   if (HasStackOverflow()) return Handle<BytecodeArray>();
   return builder()->ToBytecodeArray(isolate);
 }
 
 void BytecodeGenerator::AllocateDeferredConstants(Isolate* isolate) {
   // Build global declaration pair arrays.
   for (GlobalDeclarationsBuilder* globals_builder : global_declarations_) {
     Handle<FixedArray> declarations =
         globals_builder->AllocateDeclarations(info());
     if (declarations.is_null()) return SetStackOverflow();
@@ skipping 381 matching lines @@
 void BytecodeGenerator::VisitExpressionStatement(ExpressionStatement* stmt) {
   builder()->SetStatementPosition(stmt);
   VisitForEffect(stmt->expression());
 }
 
 void BytecodeGenerator::VisitEmptyStatement(EmptyStatement* stmt) {
 }
 
 void BytecodeGenerator::VisitIfStatement(IfStatement* stmt) {
   builder()->SetStatementPosition(stmt);
+
+  int then_slot = AllocateBlockCoverageSlot(stmt->then_range());
+  int else_slot = AllocateBlockCoverageSlot(stmt->else_range());
+
   if (stmt->condition()->ToBooleanIsTrue()) {
     // Generate then block unconditionally as always true.
+    IncBlockCounter(then_slot);
     Visit(stmt->then_statement());
   } else if (stmt->condition()->ToBooleanIsFalse()) {
     // Generate else block unconditionally if it exists.
     if (stmt->HasElseStatement()) {
+      IncBlockCounter(else_slot);
       Visit(stmt->else_statement());
     }
   } else {
     // TODO(oth): If then statement is BreakStatement or
     // ContinueStatement we can reduce number of generated
     // jump/jump_ifs here. See BasicLoops test.
     BytecodeLabel end_label;
     BytecodeLabels then_labels(zone()), else_labels(zone());
     VisitForTest(stmt->condition(), &then_labels, &else_labels,
                  TestFallthrough::kThen);
 
     then_labels.Bind(builder());
+    IncBlockCounter(then_slot);
     Visit(stmt->then_statement());
 
     if (stmt->HasElseStatement()) {
       builder()->Jump(&end_label);
       else_labels.Bind(builder());
+      IncBlockCounter(else_slot);
       Visit(stmt->else_statement());
     } else {
       else_labels.Bind(builder());
     }
     builder()->Bind(&end_label);
   }
 }
 
 void BytecodeGenerator::VisitSloppyBlockFunctionStatement(
     SloppyBlockFunctionStatement* stmt) {
@@ skipping 2672 matching lines @@
 }
 
 LanguageMode BytecodeGenerator::language_mode() const {
   return current_scope()->language_mode();
 }
 
 int BytecodeGenerator::feedback_index(FeedbackSlot slot) const {
   return FeedbackVector::GetIndex(slot);
 }
 
+int BytecodeGenerator::AllocateBlockCoverageSlot(SourceRange range) {
+  return (block_coverage_builder_ == nullptr)
+             ? BlockCoverageBuilder::kNoCoverageArraySlot
+             : block_coverage_builder_->AllocateBlockCoverageSlot(range);
+}
+
+void BytecodeGenerator::IncBlockCounter(int coverage_array_slot) {
+  if (block_coverage_builder_ != nullptr) {
+    block_coverage_builder_->IncBlockCounter(coverage_array_slot);
+  }
+}
+
 Runtime::FunctionId BytecodeGenerator::StoreToSuperRuntimeId() {
   return is_strict(language_mode()) ? Runtime::kStoreToSuper_Strict
                                     : Runtime::kStoreToSuper_Sloppy;
 }
 
 Runtime::FunctionId BytecodeGenerator::StoreKeyedToSuperRuntimeId() {
   return is_strict(language_mode()) ? Runtime::kStoreKeyedToSuper_Strict
                                     : Runtime::kStoreKeyedToSuper_Sloppy;
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8